Igniter for gas discharge pipe with a flame detection system

Abstract

An igniter for igniting waste gas discharged from a gas discharge pipe has a flame detection circuit. The igniter has an electrode and a gas conduit which supplies a source of fuel to the nozzle for creating a flame to discharge across the gas discharge pipe. A continuous DC voltage is supplied to the electrode, with any current flow between the electrode and the housing indicating the presence of a flame. Passages are provided near the electrode for circulating hot gas to reduce moisture, which could provide false readings. The internal components are mounted on a frame, which is secured in place by a locking device located at the bottom of the housing. The nozzle has a plurality of slots for the discharge of flame with the slots located at the lower end of the nozzle being of larger surface area than at the other end of the nozzle. Auxillary lines extend through the housing for discharging low volume waste gas and flame extinguishing fluid, if desired.

I claim: 
     
       1. In an igniter for a gas discharge pipe of a type having a tubular housing adapted to be mounted to the pipe, a fuel line extending into the housing for delivering gaseous fuel to a nozzle, the improvement comprising in combination: an electrode adapted to be connected to a source of electrical energy and having a tip extending into the nozzle for creating a spark to ignite the fuel;   retaining means spaced from the nozzle for securing the electrode in the housing; and   gas circulation means for circulating hot gas from the nozzle around the electrode from the tip to the vicinity of the retaining means, to remove moisture from the space surrounding the electrode between the tip and the retaining means.   
     
     
       2. The igniter according to claim 1, further including means for detecting the presence of a flame at the nozzle, comprising in combination: means for supplying a monitoring voltage to the electrode; and   means for measuring any current flow between the electrode tip and the housing in response to the monitoring voltage, the current flow indicating the presence of a flame.   
     
     
       3. The igniter according to claim 1 wherein the gas circulation means comprises: an inner annular passage surrounding the electrode and extending from the retaining means to the nozzle;   an outer passage extending from the retaining means to the nozzle; and   interconnecting passage means adjacent the retaining means, for interconnecting the inner and outer passsages, causing hot gas in the nozzle to flow through one of the passages, through the innerconnecting passage means, and back through the other passage to the nozzle.   
     
     
       4. In an igniter for gas discharge pipe of the type having a tubular housing adapted to be mounted to the pipe, a fuel line extending into the housing for delivering gaseous fuel to a nozzle, the improvement comprising in combination: an electrode having a tip extending into the nozzle;   an insulating sheath extending around the electrode to a point a selected distance from the tip;   retaining means located in the housing in surrounding and sealing contact with the sheath for retaining the electrode in the housing;   an annular passage surrounding the sheath and the electrode from the retaining means to the nozzle;   circulating passage means connected to the annular passage near the retainer means and extending to the nozzle, for allowing hot gas in the nozzle to flow through the annular passage and circulating passage means to remove moisture from the space surrounding the electrode;   power means for supplying a high DC voltage discharge to the electrode to create a spark to ignite the fuel, and for supplying a lower monitoring voltage to the electrode; and   means for measuring current flow between the electrode tip and the housing in response to the monitoring voltage, the current flow indicating the presence of a flame.   
     
     
       5. In an igniter for a gas discharge pipe of the type having a tubular housing adapted to be mounted to the pipe, a fuel line extending into the housing for delivering gaseous fuel to a nozzle, the improvement comprising in combination: an electrode adapted to be connected to a source of electrical energy and having a tip extending into the nozzle for creating a spark to ignite the fuel;   an insulating sheath extending around the electrode from its base to a point a selected distance from the tip;   retaining means located in the housing in surrounding and sealing contact with the sheath for retaining the electrode in the housing;   an inner tube coupled to the retaining means and extending to a point adjacent the nozzle, the inner tube surrounding the sheath and electrode and being of greater diameter than the sheath, defining an inner annular passage; and   an outer tube coupled to the retaining means and extending to a point adjacent the nozzle, the outer tube surrounding the inner tube and being of a greater diameter than the inner tube, defining an outer annular passage;   the inner tube having at least one hole located adjacent the retaining means, communicating the inner and outer passages with each other to allow hot gas in the nozzle to circulate through the inner and outer annular passages to remove moisture.   
     
     
       6. The igniter according to claim 5 wherein the nozzle is a tubular member having a plurality of slits for the discharge of flame and located within a tubular shield mounted to the discharge end of the housing and sealed therefrom, the outer passage communicating with the atmosphere in the shield to allow hot gas circulated through the annular passages to be discharged into the shield surrrounding the nozzle.